Device for locking the configuration of equipment such as a vehicle seat

ABSTRACT

A device for locking and unlocking the position of a moving part of a seat such as a seat on an airplane or other vehicle is disclosed. The device includes a screw and nut assembly with a clamping element. The clamping element allows movement of the moving part of the seat when the clamping element is released and holds the moving part of the seat in position when engaged.

The invention relates to devices for locking the configuration ofequipment such as a vehicle seat.

The document U.S. Pat. No. 3,398,986 discloses a device of this kindwhich enables the position of the back of a vehicle seat to be adjustedwith respect to the seat portion. The device comprises a reversiblescrew and nut system whose screw is connected to the seat. Two sets ofinterleaved plates can be connected to the seat portion and to the wholeseat respectively and are clamped together by a spring.

To incline the seat back toward the rear, the user operates an externalunlocking member which allows the nut to rotate together with all theplates. When the desired position is reached, the user releases theunlocking member, which locks the seat back in position. To raise theseat back again, the user can move it directly: this action pushes thenut against the spring and thus releases the plates. The two sets ofplates can then rotate with respect to each other. When the desiredposition is reached, the spring again clamps the plates, thus lockingthe seat back in position. This change of position is thus achievedsimply by moving the seat back, without any action on the unlockingmember.

The use of this system of interleaved friction plates has the advantageof allowing the seat back to be locked in position by means of arelatively weak spring force.

However, the device according to the cited document has the drawbackthat it only releases the plates when the seat back is raised. In fact,the user has to move the external unlocking member, as mentioned above,in order to lower the seat back toward the rear. The advantages of theplate system are therefore insufficiently exploited. Furthermore, thewhole mechanism is relatively complicated and cumbersome. In particular,the unlocking member has to be positioned on the side, so that itoccupies a large volume which may be incompatible with the spaceavailable in the vehicle passenger compartment or cabin.

One object of the invention is therefore to provide a device enabling agreater benefit to be obtained from the system of friction elements,which is arranged in a simpler and therefore less cumbersome way.

To achieve this object, according to the invention a device is proposedfor locking equipment such as a seat, comprising a support and a movingpart, the device comprising:

-   at least three elements movable with respect to each other and    connected respectively to the support and to the moving part with    spatial alternation;-   means for clamping the elements to prevent movement of the moving    part with respect to the support; and-   an unlocking member to allow movement, the unlocking member being    operable independently of the moving part, the unlocking member    being designed to cancel the clamping provided by the clamping    means.

Thus, the operation of the unlocking member makes it possible to cancelthe clamping of the elements so that the moving part can be moved inboth directions of movement as desired. The advantages of the system offriction elements are therefore exploited in the two possible directionsof movement. Furthermore, the invention enables the unlocking member tobe housed, if necessary, coaxially with respect to the main axis of thedevice, or within this axis, in such a way that the invention enablesthe device to be made with smaller overall dimensions, compatible withthe space available in a vehicle passenger compartment or cabin.

The device according to the invention can also have at least any one ofthe following characteristics:

-   it has a screw and a nut forming a reversible screw and nut    assembly, one member of the screw and nut assembly being fixed with    respect to rotation to at least one of the elements, while the other    member of the screw and nut assembly is fixed with respect to    rotation to the support;-   the screw and nut assembly is interposed between the unlocking    member and the moving part in order to transmit movement from one to    the other;-   the unlocking member extends in a main axis of the device;-   it comprises a shaft to which at least one of the elements is fixed    with respect to rotation, the unlocking member extending in a cavity    of the shaft, coaxially with the shaft;-   the unlocking member projects at an axial end of the shaft;-   it comprises a casing, at least one of the moving elements being    fixed with respect to rotation to the casing by having a shape    complementary to that of the casing;-   there are at least four elements, at least two of the elements being    connected to the moving part and at least two other ones of the    elements being connected to the support;-   the elements are plates;-   it comprises means for returning the moving part, designed to push    the moving part in a predetermined direction;-   the clamping means comprise a spring;-   the equipment is a vehicle seat, particularly an aircraft seat; and-   the moving part is a seat back.

Other characteristics and advantages of the invention are made clear inthe following description of a preferred embodiment, provided by way ofexample and without restrictive intent, with reference to the attacheddrawings, in which:

FIG. 1 is a partial side view of a vehicle seat incorporating a lockingdevice according to the invention;

FIG. 2 is a schematic view in longitudinal axial section of the lockingdevice of FIG. 1, showing its operating principle;

FIG. 3 is a detailed view in longitudinal axial section of the lockingdevice of FIG. 1; and

FIGS. 4 and 5 are views in elevation of two types of plates included inthe device of FIG. 3.

The present invention relates to mechanical devices for locking orunlocking the position of a moving part of an armchair or an articulatedbed. The device is operated by means of an external unlocking command asdescribed below.

The invention is applicable to all fields in which use is made of a bedor a seat whose elements can be positioned according to the requirementsor comfort of the user. In particular, it is applicable to seats ofvehicles such as aircraft, ships or trains, regardless of whether theseats are for drivers or pilots or passengers. It is equally applicableto domestic chairs and to beds such as hospital beds. It is alsoapplicable to furniture having moving parts, such as doors, hatches,etc. More generally, the invention is applicable in any other field inwhich a linear movement is to be locked.

In the present embodiment, the seat 2 shown in FIG. 1 is a passengerseat for aircraft. The seat comprises a seat portion 4 designed to befixed rigidly to a floor of the vehicle. The seat also comprises a back6 movable by rotation with respect to the seat portion 4 about an axiswhich is horizontal and parallel to the floor, and perpendicular to theplane of the sheet on which FIG. 1 appears. Because of thisarticulation, the back 2 can be inclined toward the rear in a known way.Finally, the seat comprises an armrest 7 connected to the seat portion4.

The seat is provided with a device 8 according to the invention enablingthe user to lock the position of the back 6 with respect to the support4. The device 8 is fixed by its front end, in other words its left-handend as seen in FIG. 1, to the support 4. It is fixed by its rear end, inother words its right-hand end as seen in FIG. 1, to one of a link 10which is pivoted at another of its ends on the back 6 in such a way thatthe movement of the back is linked to the movement of the moving partsof the device, as described below. Consequently, when the device 8 locksthe position of the back 6, the latter cannot leave its position. On theother hand, when the device unlocks the position, the back 6 can beinclined toward the front or toward the rear as desired by the user.

FIG. 2 is a schematic diagram of the device 8 which is illustrated morefully in FIG. 3. The device comprises a screw 12 formed by a shaftthreaded on its right-hand half as seen in FIG. 2. It also comprises anut 14 forming a reversible screw and nut system with the screw 12. Thenut 14 is fixed with respect to rotation to the seat portion 4 and isfixed to a connecting part 16. This part is elongate and its front endhas a cylindrical cavity which rigidly receives the nut 14 as well asthe threaded part of the screw 12 engaged in the nut. The rear end 18 ofthe connecting part 16 is pivoted by means of a strap on the aforesaidlink 10. The device comprises a second connecting part 15 receiving afront end of the screw 12. This end is mounted in a cavity of theconnecting part 15 so as to be rotatable with respect to this part whilebeing immobilized in translation with respect to it. Thus no axialmovement of the screw 12 in the part 15 is allowed. The secondconnecting part 15 is pivoted suitably at its front end 20 on the seatportion 4 about an axis perpendicular to the plane of FIG. 2. The screw12, the nut 14 and the two connecting parts 15 and 16 are coaxial aboutthe axis 22, this axis forming the longitudinal direction of the device.

As a result of this arrangement, the first connecting part 16 can onlyhave one translational movement with respect to the second connectingpart 15. In response to a force exerted in the axial direction 22 on thefirst connecting part 16, and in the direction of this force, the screw12 tends to be screwed into or out of the nut 14, thus causing the screw12 to rotate in the second connecting part 15 and thus causing the firstconnecting part 16 to be translated with respect to the secondconnecting part 15.

The device can immobilize the screw 12 with respect to rotation, thuspreventing the translation of the first connecting part 16. The devicecomprises an unlocking member 58, operated for example by means of anoperating button 26 located in the armrest 7 and operable by theoccupant of the seat. If the user does not operate the button 26, theunlocking member 58 immobilizes the screw 12, which is thus unable tomove in the nut 14. The movement of the first connecting part 16 and ofthe back 6 is consequently prevented.

The occupant's action on the button 26 is transmitted by means of acable 28 extending in the armrest 7 to the unlocking member 58 whichimmobilizes the screw 12, in order to terminate this immobilization.When the user operates the button 26, the unlocking member 58 permitsthe rotation of the screw 12 which can therefore move freely in the nutin either direction. The user can therefore incline the back 6 asdesired. As described below, this movement can also be produced simplyby means of a return spring.

The release of the button 26 locks the position of the back 6 onceagain, by immobilizing the screw 12 with respect to rotation. When theuser releases the button 26, the member 58 again prevents the rotationof the screw 12, thus fixing the position of the connecting part 16 andof the back 6.

The composition of the device 8 will now be described in greater detailwith reference to FIGS. 3 to 5.

The locking device 8 comprises a casing 15 in the shape of a rectangularparallelepiped and having an internal cavity of similar shape. Thecasing has a rear axial aperture 28 occupied by a bearing 30. A frontend of the screw 12 is housed in this bearing. The device comprises ashaft 32 having an axis 22, the rear end of the shaft being housed in aforward cavity of the screw 12 and being immobilized in the latter bymeans of a pin 34 extending perpendicularly to the axis 22 and cuttingthis axis. The screw 12 and the shaft 32 are therefore fixed rigidly toeach other.

The shaft 32 extends along the axis 22 through the casing 15 so that itsfront end occupies a forward aperture of the casing with theinterposition of a bearing 36. At its two ends, the shaft 32 has anouter diameter which is reduced with respect to the diameter of a medianportion of the shaft. The device comprises two stops 38 and 40 ofcircular shape, each having a central aperture, threaded onto the frontand rear portions respectively of the shaft 32. Each stop thereforebears on a corresponding shoulder delimiting the median portion of theshaft 32 and on a corresponding axial end face of the casing 15. As aresult of this assembly, the shaft 32 and the screw 12 are rotatablewith respect to the casing 15 about the axis 22 but are immobilized intranslation with respect to this casing.

The bearings 30 and 36 and the stops 38 and 40 can be plain, or can bemade from sintered material, or in the form of ball bearings, needlebearings, or the like.

The device 8 comprises two sets of friction plates shown in FIGS. 3 to5. The plates 42 of the first set, shown in FIG. 4, are disk-shaped witha central circular aperture 44. There are four of these plates in thepresent example. However, this number could be increased or decreased.Each plate 42 has two lugs 46 projecting radially into the aperture 44from an edge of this aperture. Each lug has a generally rectangularshape and extends in the plane of the plate. The shaft 32 has tworectilinear longitudinal grooves extending parallel to the axis 22 onthe outer face of the shaft and diametrically opposite each other oneither side of this axis. Each of these grooves can receive one of thelugs 46 when the plates 42 are threaded onto the shaft 32. In thisposition, each plate extends in a plane perpendicular to the axis 22,the plates being parallel to each other. As a result of thisarrangement, the plates 42 are movable in translation along the shaft 32and inside the casing 15. However, they are fixed with respect torotation to the shaft 32. They therefore accompany the latter in itsmovement when it rotates inside the casing 15.

The plates 48 of the second set, shown in FIG. 4, have a generallyrectangular shape, or more precisely a square shape in the presentexample. Each of them has a central circular aperture 44. The outerprofile of these plates matches the shape of the cavity of the casing 15in a plane perpendicular to the axis 22. The plates 48 can therefore bereceived in the casing 15 by being threaded onto the shaft 32 andextending parallel to each other and perpendicularly to the axis 22. Asa result of the complementary shapes of the plates 48 and the cavity ofthe casing 15, the plates are immobilized in rotation with respect tothe casing about the axis 22 by the complementarity or interaction oftheir shapes, but are free to slide along this axis. The number ofplates 48 of the second set is also four, but this number could also bechanged, particularly to match the number of plates in the first set.

The plates 42 and 48 of the two sets alternate spatially, in other wordsalong the axis 22, in such a way that all the plates are parallel toeach other and perpendicular to the axis 22. The plates of the two setsare in contact with each other, by making surface contact.

Clearly, various means can be provided to immobilize the plates of thefirst set in rotation with respect to the shaft and to immobilize theplates of the second set in rotation with respect to the casing. Inparticular, splines, channels, flats or any other shape can be used topermit this immobilization in rotation while allowing relative movementalong the axis 22.

The device also comprises two rings 50 and 52, each threaded onto theshaft 32 and interposed, respectively, between the front stop 38 and thefirst plate 42, and between the last plate 48 and the rear stop 40.

The device comprises a return spring 54 interposed axially between therear ring 52 and the rear stop 40 and having its ends bearing on thesecomponents. This spring 54 presses the plates 42 and 48 of the two setsagainst each other so as to clamp them when the unlocking member 58 isnot operated. In these conditions, at rest, the frictional torquebetween the plates opposes the rotation of the shaft 32 and the screwwith respect to the casing 15, thus immobilizing the back 6 in itsposition.

The casing 15 is extended forward from its aperture by an arm 56 whichis, for example, fixed rigidly in this aperture by means of a screw andnut joint. The unlocking member comprises a pusher 58 having a rodextending inside the arm 56, in a cavity of the latter, coaxially withthe arm and along the axis 22. A pin 60 extending transversely withrespect to the axis 22 and cutting the latter extends in an opening ofthe shaft 32 and passes through two radial apertures of the rear ring52. A rear end of the pusher 58 bears on this pin, a front end of thepusher also projecting at the front end of the arm 56. The pusher 58 canslide along the axis 22 with respect to the arm 56 to push the pin 60toward the rear. The user makes the pusher 58 slide toward the rear byoperating the button 26, with the aid of the cable 28 and by means of aknown arrangement which is not described in detail here.

As long as the pusher 58 is not operated, the spring 54 presses the twosets of plates against each other in such a way that the frictionaltorque thus generated prevents the rotation of the plates 42 of thefirst set and of the screw 12. The device 8 then prevents any movementof the back 6 of the armchair which is thus locked in its position.

When the user presses the button 26, the backward movement of the pusher58 pushes the rear ring 52 toward the rear, thereby compressing thespring 54 and releasing its pressure on the two sets of plates. Thefrictional torque between the plates then decreases greatly and ceasesto oppose the rotation of the screw 12 which can thus move in the nut14. The user can then move the seat back 6, by pushing it with his backfor example, to the desired position in the forward or rearwarddirection, any position being obtainable.

When the user releases the button 26, the spring 54 returns the wholeassembly consisting of the rear ring 52 and the pusher 58 toward thefront, and clamps the plates again. The screw is then immobilized inposition again, together with the back 6.

It should be noted that the device can be unlocked while under load andregardless of the size of this load. The path of the pusher 58 can bevery short, since it is sufficient to cancel the pressure of the spring54 in order to allow the plates to rotate with respect to each otherwithout necessarily releasing them completely from each other.

The device comprises another return spring 62 interposed axially betweenthe rear end face of the casing 15 and an elastic ring 64 fitted in anouter annular groove formed on the first connecting part 16, this springbearing axially on these components. The spring therefore exerts a forcetending to move the first connecting part 16 away from the secondconnecting part 15. This spring is designed to have sufficient stiffnessto push the seat back 6 to its limit position, for example the highestposition, when the user unlocks the device while ceasing to push on theseat back or while pushing moderately on it. This return spring enablesthe seat back to accompany the user's back at all times when he wishesto raise it by operating the button 26, thus limiting the force requiredfrom the user.

In the present example, a rear end of the screw 12 has a tap receiving ascrew 66 whose head diameter is greater than the overall diameter of therear part of the screw 12, thus enabling the screw 66 to bear axially onthe rear end of the nut 14. The screw 66 forms a stop screw which fixesthe limit position of the seat back 6. This position is determined, inparticular, by the length of the threaded part of the screw 12.

The plates 42 and 48 can be formed from various materials which providea maximum coefficient of friction, with low wear and without anytendency to adhere to each other. The number of the plates depends onthe desired braking torque.

It should be noted that the device according to the invention can beused to lock the seat back 6 in an unlimited number of positions and inany position between the two limits of travel of the seat back.

Clearly, numerous modifications can be made to the invention withoutdeparture from the scope thereof as defined by the attached claims. Thescrew 12 can be made in the form of a ball screw. In a variantembodiment, the elements 42 and 48 can have a shape which is not flat,for example a corrugated shape.

1. A device for locking the configuration of equipment, the equipmenthaving a support and a moving part, the device comprising: at leastthree plates, said plates being movable with respect to each other andsaid plates being connected respectively to the support and to themoving part, wherein the plates alternate spatially; a screw and a nutforming a reversible screw and nut assembly, one member of the screw andnut assembly being fixed with respect to rotation to at least one of theplates connected to the moving part, while a second member of the screwand nut assembly is fixed with respect to rotation to the support; meansfor clamping the plates to prevent a movement of the moving part withrespect to the support; and an unlocking member to allow movement,wherein the unlocking member is operable independently of the movingpart, the unlocking member is designed to cancel the clamping providedby the clamping means, and the unlocking member extends in a main axisof the device.
 2. The device according to claim 1, wherein the screw andnut assembly is interposed between the unlocking member and the movingpart in order to transmit movements from one to the other.
 3. The deviceaccording to claim 1, further comprising a shaft to which at least oneof the elements is fixed with respect to rotation, the unlocking memberextending in a cavity of the shaft, coaxially with the shaft.
 4. Thedevice according to claim 3, characterized in that the unlocking memberprojects at an axial end of the shaft.
 5. The device according to claim1, further comprising a casing, wherein at least one of the movingplates is fixed with respect to rotation of the casing by having a shapecomplementary to that of the casing.
 6. The device according to claim 1,wherein there are at least four plates, at least two of the plates beingconnected to the moving part and at least two other ones of the platesbeing connected to the support.
 7. The device according to any claim 1,further comprising means for returning the moving part, said means beingdesigned to push the moving part in a predetermined direction.
 8. Thedevice according to claim 1, wherein the clamping means comprises aspring.
 9. The device according to any one of the preceding claims,wherein the equipment is a vehicle seat, particularly an aircraft seat.10. The device according to claim 1, wherein the moving part is a seatback.